The International CBX Owners Association

Make 3 Brake shim pads from discarded beer cans for 79-80 CBX.
Trace and Cut from a beer can for even brake pad wear.
It's about the same thickness as a shim that retails for € 8.00 or $10. (a beer can wall thickness is 0.097 mm)
"We recommend the use of this item as part of your brake overhaul strategy for brake pad renewal.
It is inexpensive and will ensure everything is spaced and shimmed correctly."

Clever, neat. And, with a secondary benefit! (Gotta 'find' an empty beer can!)

But if you are in the process of buying some parts from "www.cmsnl.com" anyway I'd go with certified parts.